Process for applying liquid to sheets of fiber



y 12, 1970 J. L. CARDER 3,511,730

PROCESS FOR APPLYING LIQUID TO SHEETS 0F FIBER Filed April 6. 1967 F l G R 0 m R D M R A C b U o L Y M W J AGENT 3,511,730 PROCESS FOR APPLYIlFEIEEkIQUID T SHEETS 0F Jimmy Louis Carder, Camden, S.C., assignor to E. I. du Pont de Nemours and Company, Wilmington, Del., a corporation of Delaware Filed Apr. 6, 1967, Ser. No. 628,879 Int. Cl. B05c 8/04 US. Cl. 156-163 7 Claims ABSTRACT OF THE DISCLOSURE This invention relates to a process for applying liquid to sheets of fiber, especially to a continuously moving tow of continuous filaments.

BACKGROUND OF THE INVENTION In the application of liquids such as finishes, antistatic agents, and other coating compositions to moving sheets of fibers, the sheet of fibers may be wet thoroughly by passing it through a bath of the liquid; but there is no positive control of the amount of liquid applied to the fiber. To obtain such positive control, Latour described in his US. Pat. 3,199,492 the method of metering liquid onto a moving sheet of fibers by passing the liquid at a constant rate through a slot in a plate over which the fiber sheet is being passed. However, although application of the liquid may be set at a constant rate on a grOSS basis by metering, improved uniformity of application on a fiber-to-fiber basis has been desired. Hitherto, when dense sheets of fibers have-been treated in this way, a

significant portion of the product has frequently been found to have received only a small amount or none of the treating liquid. The liquid has been applied to each side of the sheet of fibers in turn, but penetration to the center of the sheet is difiicult.

STATEMENT OF THE INVENTION PREFERRED EMBODIMENTS In preferred embodiments, the liquids applied are liquids such'as textile finishes, antistatic agents, and other coating compositions. One or more of such liquids may be applied, separately or simultaneously if desired. These li uids are preferably applied to continuously moving eets of fibers. Although the fiber may be staple or con- United States Patent 0 ice tinuous length, application to continuous filament tow is preferred.

Conventional modes of liquid application may be employed. Suitable liquid applicators will be apparent to those skilled in the art. The liquid is applied to one side of each of the sheets and penetrates the surface of the sheets in varying degrees. Such penetration may provide liquid to the interior portions of the sheet and may even penetrate to the opposite side of the sheet. Application of liquid to both sides of each sheet may be employed, but such is neither essential nor necessarily desirable to the practice of this invention. Applicators which apply liquid at a predetermined uniform (gross basis) rate are preferred. Still more preferred are such applicatorswhich have a'grooved surface. Most preferred are such grooved applicators with a smooth take-off surface for the fiber sheet. These grooved applicators will be described in greater detail hereinafter.

The sheets are converged with their wetted sides together. A suitable means of providing convergence is the tension bar exemplified in the figures. Such exemplification is not intended as limitative; other convergence means such as the nip of a pair of squeeze rolls may suitably be employed.

The sheets may be simultaneously forced into contact at the point of convergence or separately forced into contact thereafter. Simultaneous convergence and forcing into contact is preferred as exemplified by the tension bar shown in the figures. Sutlicient tension forcing the convergence of two continuously moving sheets of fiber against the tension bar can provide suflicient force to cause liquid to pass from the interior of the converged sheets to the exterior portions thereof. The application of force to the converged sheets may be provided by pressure means such as squeeze rolls at the point of convergence or at a point after convergence. Similarly, successive applications of force, such as passage through two or more squeeze rolls, is suitable.

The amount of force that is necessary in a particular application depends on variables such as the-liquid properties (e.g. density) and the properties of the sheet of fibers (e.g. thickness). Such force must be sufiicient to cause some of the liquid to pass from interior to exterior portions of the converged sheets. The optimum force necessary can easily be determined by routine experimentation and measurement of distribution on a fiber-to-fiber basis. If too low a force is applied, insufficient amounts of liquid will pass to the exterior portions of the converged sheets and the interior portions thereof will contain a greater amount of liquid. If too great a force is applied the liquid may be forced to the exterior portions of the converged sheets and be deposited on the force applying means. Although in the latter case, a slight reduction in the rate of liquid application (on a gross basis) may result, such is not necessarily undesirable in that the liquid may be reapplied to these exterior portions and result in a more uniform application (on a fiber-to-fiber basis) to the sheets.

DRAWINGS manner in which the process of the invention is carried out;

the uniformity of liquid .FIG. 4.

FIG. 6 illustrates the contact of a fiber sheet with the grooved fluid application of FIGS. 4 and 5.

Considering each of the figures more specifically, FIG.

-- 1 illustrates a sheet of fibers 1 being passed over applicator 3 for applying liquid and a sheet of fibers 2 being passed simultaneously under applicator 3', identical with applicator 3 but turned upside-down and end-for-end. From each applicator liquid is applied to the moving sheet of fibers from outlet means 4, the liquid being delivered by way of interior supply chamber 5 from inlet port 6. The fiber sheets are opened by grooves 7 as the sheet passes in contact with the outlet means. The two sheets of fibers are converted together by passing them under tension bar 8 to form a single sheet of fibers 9, double the size of the initial fiber sheets. The forced contact of these converged sheets causes the diffusion or passage of liquid from the finterior to the exterior portions of sheet 9; the extent of such diffusion or passage depends on the force applied.

Sheet 9 is brought half-way around roll 10 and between rolls 1-0 and 11 with application of pressure, then between rolls 11 and 12, again with application of pressure. The squeezing of the fiber sheets as it passes between these rolls either initiates the ditfusi'on or passage of the liquid from the interior portion of the sheet 9 to the fibers in its outer faces or such squeezing further causes the passage thereof'From' rolls 11 and 12 the sheet of fibers, with the liquid uniformly applied throughout, is forwarded to the next processing stage (not shown), such as cutting to staple fibers.

FIGS. 2 and 3 illustrate a preferred applicator 3 in more i detail, "showing how it is comprised of cylinder 13 with a longitudinal slot 14 parallel to its axis as the outlet means. The surface of the cylinder contains grooves 7 on the side of the slot. upon which the sheet of fibers is led in across the slot. A smooth surface 15 is provided on the other side of the slot, i.e., the side from which the sheet of fibers is taken off after passing in contact with the slot. The right-hand portion of the cylinder is seen in crosssection, illustrating interior supply chamber 5 and inlet port 6, which may also be seen in FIG. 3. Collars 16 limit the spread of the sheet of fibers to thewidth of the longitudinal slot.

FIGS-4 and 5 illustrate a suitable cylinder 17 having another type of outlet means. T he cylinder is similar to the cylinder previously described except that the outlet means comprises channels 18 terminating in orifices 19 at the roots and orifices 20 at the crests of the grooves 21, which in this embodiment extend slightly past the outlet means.

- Such grooved applicators are preferred in that the liquid is also applied to interior portions of the sheet of fibers, as shown in FIG. 6, by penetrating of the surface of the sheet by the grooves 21 instead of simply to the surface .of the sheet. This provides an improved distribution of liquid (fiber'to-fiber basis) and enhances the uniform distribution provided by the process of this invention. A

smooth fiber take-off portion on such applicators reduces the filament breakage.

' The liquid is delivered at a constant predetermined rate The following example, although not intended to be limitative, illustrates a process in accordance with the present invention in actual operation. Parts and percentages are by weight unless otherwise indicated.

EXAMPLE A dimethylformamide solution containing 40% by weight of a copolymer of 10% glycidyl methacrylate and 4-nonylphenoxypoly(ethyleneoxy)ethylene acrylate, in which the poly(ethyleneoxy) segment contains about 40 units, is dispersed in a solution of 1 part of tris-1,3,5- (dirnethylaminomethyl)phenol in 510 parts of demineralized water to provide an aqueous emulsion containing 3.0% by weight of the copolymer.

An applicator system constructed in accordance with FIGS. 1 to 3 is used to apply the aqueous emulsion as an antistatic treating liquid to two sheets of continuous filament acrylonitrile polymer tow, each containing approximately 125,000 filaments at a constant rate of 2750 cc./ min. to each tow with the tow moving at y.p.m. (109 meters per min.). The tows are converged at a tension bar with their wetted sides together, passed through three forwarding rolls (two nip positions as shown in FIG. 1) under pressure, and cut to staple fibers. The staple fibers are analyzed for solids pick-up, and it is found that various samples of the fibers exhibit a range of 1.24% to 1.31% solids pick-up (average 1.28%). By contrast, a range of 1.06% to 1.27% solids pick-up (average 1.13%) is observed when the same liquid is applied at the same rate to two sheets of tow moving at the same speed as above, with the exceptionthat the liquid is applied from two smooth-surfaced, slotted applicators side-by-side, with the two sheets of tow being combined subsequently side-by-side into a single tow sheet on the three forwarding rolls with the same pressure applied and thence cut to staple fibers in the same manner. This illustrates an increased gross basis distribution, and more significantly, a more uniform fiber-to-fiber distribution.

UTILITY prising: applying liquid to one side and to the interior portions of each of two sheets of fiber by contacting the said sheets of fiber with the grooved surface of a liquid applicator, the outer surface of said liquid applicator having a grooved portion and a smooth portion, said grooved portion having grooves running in the direction of the movement of said sheets of fiber, smoothly removing said sheets of fiber from the smooth portion of said liquid applicator, converging the wetted sides of the sheets together, and forcing the wetted sides into contact with each other to cause liquid to pass from the interior of the converged sheets to the exterior portions thereof.

2. Process according to claim 1 wherein said sheets of fiber are continuously moving during the application of liquid and are converged while the sheets are under tension.

3. Process according to claim 1 wherein the said converging and forcing are simultaneously effected.

4. Process according to claim 1 wherein said liquid is applied uniformly at a predetermined rate.

5. Process according to claim 1 wherein said sheets of fiber are continuous filament tow.

6. Process according to claim 1 wherein said liquid is a textile finishing coating composition.

- 6 7. Process according to claim 1 wherein said liquid 3,371,000 2/1968 Davenport et a1 1561 80 is an antistatic agent coating composition. 3,393,661 7/1968 Sharp 118411 References Cited RALPH S. KENDALL, Primary Examiner UNITED STATES PATENTS 5 Us. CL XR. 2,338,960 1/1944 Nottebohm.

3 326 1 1 I /19 Kineen 11 11 14 5 156 166 

